1. Field of the Art
The present invention relates generally to a chemical formulation used in semiconductor wafer fabrication and particularly to a chemical formulation that is utilized to remove residue from wafers following a resist ashing process. More specifically, the present invention relates to a cleaning formulation for removal of residue from semiconductor wafers containing delicate copper interconnect and low-k or ultra low-k interlayer dielectrics structures.
2. Description of the Prior Art
As semiconductor wafer designs become smaller, Cu interconnect and low-k or ultra low-k interlayer dielectrics are being developed to improve device performance. For example, Cu/low-k single damascene or dual damascene wafers are being fabricated by etching and ashing process.
The prior art tells the utilization of various chemical formulations to remove residue and clean wafers following a resist ashing process. Some of these prior art chemical formulations are based on alkaline amines (U.S. Pat. No. 5,334,332) and ammonium fluoride (EP patent No. 662705). Still other chemical formulations are based on organic carboxylic acids (U.S. publication No. 2003/0143495 A1). These various prior art chemical formulations have drawbacks that include unwanted removal of metal like Cu or low-k and ultra low-k insulator layers whose k-value are less than 3.0. There is therefore a need for chemical formulations that effectively remove residue following a resist ashing process and do not affect on metal and low-k and ultra low-k insulator layers.